How do you evaluate the definite integral #int (3x^2) dx# from #[1,2]#?

1 Answer
Oct 13, 2016

I found #7#

Explanation:

We first evaluate the indefinite integral to find the function called the Primitive; then we evaluate the primitive at the extremes and subtract the vales.
In your case we have:

#int_1^2(3x^2)dx=cancel(3)x^3/cancel(3)=x^3# which is the Primitive;

we now evaluate it at #2 and 1# and subtract the values obtained:

#(2^3)-(1^3)=8-1=7#